# Variable Setup The items on this page can all be configured on the **Name and Setup** step of the Variable dialog.
A screenshot of the Setup step of the new Variable dialog, containing several steps

Variable dialog | Name and Setup step

## Name There are no restrictions to how you name your Variables, as long as the name isn't blank. Make them as readable and self-explanatory as possible and thank yourself later! {% hint style="info" %} Bear in mind that if you will be generating Excel from your Model, Variable names will be written in the spreadsheet, meaning you should avoid choosing a name that Excel will interpret as a formula, otherwise you will run into problems. But if you really want to start a name with an "=", we won't stop you. {% endhint %} ## Variable type There are three types of variables in Models: 1. Assumption 2. Calculation 3. Aggregation The **Variable type** you choose determines the default way that the Variable will calculate its value. Variables can calculate values from both **Assumptions** and **Calculations** in different periods of the model by using Time Segments. See the [**dedicated help section on Time Segments**](https://help.taglo.io/variables/time-segments) for more details. **Aggregation** Variables must calculate value via aggregation for the entire model period. ### Assumption Variables Assumption Variables are usually the starting point of your Model. They reference the basic inputs, called Assumptions, that underpin your Model's calculations. Read more on how Assumptions work [**here**](https://help.taglo.io/assumptions)**,** and how to reference them from your Variable [**here**](https://help.taglo.io/assumptions/creating-referencing-assumptions). ### Calculation Variables Calculation Variables obtain their values by referencing other Variables and performing a calculation. e.g. `Profits = Revenues - Costs.` Read more about Calculations [**here**](https://help.taglo.io/calculations)**.** ### Aggregation Variables {% hint style="warning" %} You will only see the **Aggregation** option if you have already selected one or more [**Dimensions**](#dimensions) for your Variable ([see below](#dimensions)). {% endhint %} Aggregation allows you to bring values from several separate Variables together into a single Variable. Read more about Aggregation [**here**](https://help.taglo.io/aggregation). ## Dimensions Select any [**Dimensions**](https://help.taglo.io/dimensions/introduction-to-dimensions) that you want to apply to your Variable. Dimensions allow you to work with a collection of items without having to repeat calculations. > For example, a Dimension might be: > > * **Widget Model** | Model A, Model B, and Model C > > or > > * **Sales Region** | North, East, West, and South Dimensions are extremely powerful, time-saving, and improve the quality of your Models. Read more about how to use Dimensions [**here**](https://help.taglo.io/dimensions/introduction-to-dimensions). ## Number Format A Number Format determines how the calculated values for your Variable will be displayed. You can choose from inbuilt Number Formats or create your own. Any Assumptions you create from within the Variable will use the same Number Format by default. Read more about Number Formats [**here**](https://help.taglo.io/number-formats). ## Data Type Models works with several Data Types, which affect how values are treated in calculations. These include Data Types for working with numerical values, text values, date-time values and others. Read more about the different Data Types and how to work with them [**here**](https://help.taglo.io/data-types). ### Validation Dimension The Validation Dimension step will only appear if you select the `Validation` **Data Type**. Validation allows you to select inputs from a list of values. > For instance, a Variable called `Include tax?` may be an Assumptions Variable where you want to choose between `Yes/No` options. To achieve this, select the `Validation` Data Type, and then select the inbuilt `Yes/No Option` Dimension in the Validation Dimension step. The Validation chosen here will be applied to any Assumptions created from this Variable. You can use any Dimension for Validation. ## Time Period You may want to see outputs from your Model on a different timescale to that defined in the Model [**Timings**](https://help.taglo.io/models/home-tab/creating-a-model/timings). > For instance, for a Model built on a Monthly basis, you may want to see outputs in Quarters or Years How Models calculates the value for each aggregated period depends on the Unit of the Variable. `Balance` Variables will calculate the value at the end of the period, and `Flow` Variables will sum the values of intervening periods. Read more about `Balance` and `Flow` concepts in the [**Units documentation**](https://help.taglo.io/units). {% hint style="info" %} If you select a Time Period other than `Default`, your Variable will automatically be a Calculation Variable, and you will not be able to edit [**Time Segments**](https://help.taglo.io/variables/time-segments). {% endhint %} ## Tags You can Tag Variables just like any other taggable item in Taglo software, which will allow you to filter the list of Variables by those Tags. Read more about Tags and tagging [**here**](https://help.taglo.io/tags).